1. Field of the Invention
The present invention relates to an escapement or directional latching mechanism for a timer which actuates a timing switch component through the intermediary of a driving member, which is manually settable relative to the driving member against a larger moment of resistance in one direction of rotation as in the other direction of rotation; wherein the escapement includes a ring having an internal toothing coupled with the driving member, and a ratchet wheel connected secured fixed against rotation with the timing switch component and which is located coaxially with the ring, with the ratchet wheel including at least two arms located in the plane of the ring, which with a finger thereof engage spring-elastically in the radial direction into the internal toothing, and which finger upon a displacement in one or the other direction of rotation is forced out of engagement with the internal toothing, whereby the pairing constituted of the internal toothing and the finger is provided with on the first pairing portion with tooth sides which are angularly symmetrical relative to the radius of the ring.
2. Description of the Prior Art
An escapement or directional locking mechanism of the type considered hereinabove is described in the disclosure of German Pat. No. 29 15 526. The manual rotation of the timing switch component for time setting encounters only a low movement of resistence from the escapement, so that the manually effected time setting necessitates only a low application of force. In the opposite direction of rotation, the moment of resistance is substantially higher, so that the driving member exerts a sufficiently high drag moment on the timing switch component for the effectuation of the respective switching procedures. At a forcible rotation of the timing switch component opposite to the actual setting direction, the fingers are also displaced from engagement with the internal toothing so as to avoid the danger of damaging the escapement.
In German Pat. No. 29 15 526, the moments of resistance which are different in both direction of rotation are obtained in that two articulated connections are formed on the arm, which are at a different operative spacing relative to the finger. That type of construction of the ratchet wheel is quite complex in its actual configuration. This is also applicable when the ratchet wheel is formed as a unitary plastic component, for example, an injection-molded plastic component; in which the articulated connections are formed by a reduction of the cross-section of the arm. In this instance, the bending elasticity each of the reduced cross sectional zones must be correlated with each other. When the bending is restricted to small areas of the arm, then the plastic material in these zones tends to exhibit fatigue phenomena.
In the disclosure of German Pat. No. 28 13 069 there is described an escapement mechanism in which, during a forcible rotation or turning of the timing switch component, the latter is destroyed when rotated opposite to its actual setting direction.